gPlanarity is a planar graph untangling puzzle
game. The objective is to untangle the initial
mess on the board by dragging vertices to
eliminate crossed lines. Bonus points are awarded
for quick work and for exceeding the objective.
The gameplay is identical to a Flash game called
Planarity, but new UI and puzzle features were
added, such as expanding or shrinking the board,
selecting and dragging in groups, reseting the
board, free level navigation, multiple level
generation algorithms, puzzles with different win
conditions, intersection highlighting, and more.

gauztris is a Tetris clone with High Score support
that compiles on Linux/FreeBSD/Solaris and
probably more. It was created to fill the void of
console tetris clones that will compile on
non-Linux platforms.

gnomeGo is a very simple but nice GUI that allows
a player to play the game of go (also known as
igo, baduk, or weiqi) against gnuGo. There is also
support for multi-player games. Three board sizes
are supported. This go GUI provides GNOME
integration.